FIG. 1 depicts a typical dimmer circuit 100 comprising a source of electrical energy or power supply 112, a dimmer 114, and a lighting load 116. The lighting load 116 may be a lamp set comprising one or more lamps adapted to be connected between the hot and neutral terminals of a standard source of electrical energy. The lamp set may include one or more incandescent lamps and/or other lighting loads such as electronic low voltage (ELV) or magnetic low voltage (MLV) loads, for example.
The power supply 112 supplies an electrical waveform to the dimmer 114. The dimmer regulates the delivery of electrical energy from the power supply 112 to the lighting load 116. The dimmer 114 may include a controllably conductive device 118 and a control circuit 120. The controllably conductive device 118 may include an input 122 adapted to be coupled to the power supply 112, an output 124 adapted to be coupled to the lighting load 116, and a control input 126. The control circuit 120 may have an input 128 coupled to the input 122 of the controllably conductive device 118 and an output 130 coupled to the control input 126 of the controllably conductive device 118.
A typical, AC, phase-control dimmer regulates the amount of energy supplied to the lighting load 116 by conducting for some portion of each half-cycle of the AC waveform, and not conducting for the remainder of the half-cycle. Because the dimmer 114 is in series with the lighting load 116, the longer the dimmer 114 conducts, the more energy will be delivered to the lighting load 116. Where the lighting load 116 is a lamp set, the more energy delivered to the lighting load 116, the greater the light intensity level of the lamp set. In a typical dimming scenario, a user may adjust a control to set the light intensity level of the lamp set to a desired light intensity level. The portion of each half-cycle for which the dimmer conducts is based on the selected light intensity level.
The controllably conductive device 118 may include a solid state switching device, which may include one or more triacs, which may be thyristors or similar control devices. Conventional light dimming circuits typically use triacs to control the conduction of line current through a load, allowing a predetermined conduction time, and control the average electrical power to the light. One technique for controlling the average electrical power is forward phase control. In forward phase control, a switching device, which may include a triac, for example, is turned on at some point within each AC line voltage half cycle and remains on until the next current zero crossing. Forward phase control is often used to control energy to a resistive or inductive load, which may include, for example, a magnetic lighting transformer.
Because a triac device can only be selectively turned on, a power-switching device, such as a field effect transistor (FET), a MOSFET (metal oxide semiconductor FET), or an insulated gate bipolar transistor (IGBT), for example, may be used for each half cycle of AC line input when turn-off phase is to be selectable. In reverse phase control, the switch is turned on at a voltage zero-crossing of the AC line voltage and turned off at some point within each half cycle of the AC line current. A zero-crossing is defined as the time at which the voltage equals zero at the beginning of each half-cycle. Reverse phase control is often used to control energy to a capacitive load, which may include for example, an electronic transformer connected low voltage lamp.
The switching device may have a control or “gate” input 126 that is connected to a gate drive circuit, such as an FET drive circuit, for example. Control inputs on the gate input render the switching device conductive or non-conductive, which in turn controls the energy supplied to the load. FET drive circuitry typically provides control inputs to the switching device in response to command signals from a microcontroller. FET protection circuitry may also be provided. Such circuitry is well known and need not be described herein.
The microcontroller may be any processing device such as a programmable logic device (PLD), a microprocessor, or an application specific integrated circuit (ASIC), for example. Power to the microcontroller may be supplied by a power supply. A memory, such as an EEPROM, for example, may also be provided.
Inputs to the microcontroller may be received from a zero-crossing detector. The zero-crossing detector determines the zero-crossing points of the input waveform from the power supply 112. The microcontroller sets up gate control signals to operate the switching device to provide voltage from the power supply 112 to the load 116 at predetermined times relative to the zero-crossing points of the waveform. The zero-crossing detector may be a conventional zero-crossing detector, and need not be described here in further detail. In addition, the timing of transition firing pulses relative to the zero crossings of the waveform is also known, and need not be described further.
FIGS. 2A and 2B depict an example lighting control device, or “dimmer,” 114 that may be programmable in accordance with the invention. As shown, the lighting control device 114 may include a faceplate 12, a bezel 13, an intensity selection actuator 14 for selecting a desired level of light intensity of a lighting load 116 controlled by the lighting control device 114, a control switch actuator 16, and an air gap actuator 17. Faceplate 12 need not be limited to any specific form, and is preferably of a type adapted to be mounted to a conventional wall box commonly used in the installation of lighting control devices. Likewise, bezel 13 and actuators 14, 16, and 17 are not limited to any specific form, and may be of any suitable design that permits manual actuation by a user.
Actuation of the upper portion 14a of actuator 14 increases or raises the light intensity of lighting load 116, while actuation of lower portion 14b of actuator 14 decreases or lowers the light intensity. Actuator 14 may control a rocker switch, two separate push switches, or the like. Actuator 16 may control a push switch, though actuator 16 may be a touch-sensitive membrane or any other suitable type of actuator. Actuators 14 and 16 may be linked to the corresponding switches in any convenient manner. The switches controlled by actuators 14 and 16 may be directly wired into the control circuitry to be described below, or may be linked by an extended wired link, infrared link, radio frequency link, power line carrier link, or otherwise to the control circuitry.
Air gap actuator 17 is provided in order to open an air gap switch in the lighting control device 114. The air gap switch disconnects the power supply 112 from the controllably conductive device 118, the control circuit 130, and the lighting load 116. The air gap switch is opened by pulling the air gap actuator 17 away from the faceplate 12 of the lighting control device 114.
Lighting control device 114 may also include an intensity level indicator in the form of a plurality of light sources 18. Light sources 18 may be light-emitting diodes (LEDs), for example, or the like. Light sources 18 may occasionally be referred to herein as LEDs, but it should be understood that such a reference is for ease of describing the invention and in not intended to limit the invention to any particular type of light source. Light sources 18 may be arranged in an array (such as a linear array as shown) representative of a range of light intensity levels of the lighting load being controlled. The intensity levels of the lighting load may range from a minimum intensity level, which is preferably the lowest visible intensity, but which may be zero, or “full off,” to a maximum intensity level, which is typically “full on.” Light intensity level is typically expressed as a percent of full intensity. Thus, when the lighting load is on, light intensity level may range from 1% to 100%.
By illuminating a selected one of light sources 18 depending upon light intensity level, the position of the illuminated light source within the array may provide a visual indication of the light intensity relative to the range when the lighting load being controlled is on. For example, seven LEDs are illustrated in FIGS. 2A and 2B. Illuminating the uppermost LED in the array may indicate that the light intensity level is at or near maximum. Illuminating the center LED may indicate that the light intensity level is at about the midpoint of the range. Any convenient number of light sources 18 may be used, and it should be understood that a larger number of light sources in the array will yield a commensurately finer gradation between intensity levels within the range.
When the lighting load 116 being controlled is off, the LED representative of the intensity level at which the lighting load will turn on to may be illuminated at a relatively high illumination level, while the remaining light sources may be illuminated at a relatively low level of illumination. This enables the light source array to be more readily perceived by the eye in a darkened environment, which assists a user in locating the lighting control device 114 in a dark room, for example, in order to actuate the lighting control device 114 to control the lights in the room. Still, sufficient contrast may be provided between the level-indicating LED and the remaining LEDs to enable a user to perceive the relative intensity level at a glance.
Lighting control device 114 may include a standard back box 20 having a plurality of high voltage screw terminal connections 22H, 22N, 22D that may be connections for hot, neutral, and dimmed hot, respectively.
Such lighting control devices typically provide certain features such as, for example, protected preset, fading, and the like. Some such lighting control devices may enable a user to set a value associated with a feature the lighting control device provides. For example, lighting control devices are known that enable a user to set a light intensity value associated with the “protected preset” feature (see, for example, U.S. Pat. No. 6,169,377, which describes a lighting control unit having the protected or “locked” preset feature).
Protected preset is a feature that allows the user to lock the present light intensity level as a protected preset light intensity level to which the dimmer should set the lighting load 116 when turned on by actuation of actuator 16. After a protected preset is assigned by a user, the protected preset feature is considered enabled. The user can also disable (or unlock) the protected preset.
When the dimmer is turned on via actuator 16 while protected preset is disabled, the dimmer will set the lighting load 116 to the intensity level at which the dimmer was set when the lighting load was last turned off. Accordingly, when the lighting load 116 is turned off via actuator 16, the light intensity level at which the lighting load was set is stored in memory. When the lighting load 116 is turned on via actuator 16, the microcontroller reads from memory the value of the last light intensity level, and causes the lighting load to be set to that level.
When the dimmer is turned on via actuator 16 while protected preset is enabled, the dimmer will set the lighting load 116 to the protected preset intensity level. When the lighting load 116 is turned off via actuator 16, the light intensity level at which the lighting load was set is not stored in memory. When the lighting load 116 is turned on, the microcontroller reads the protected preset intensity level value from memory and causes the lighting load to be set to the protected preset level.
To enable the protected preset feature by locking the present light intensity level as the protected preset intensity level, a user may follow the following procedure. First, actuator 14 may be used to set the lighting load to a desired intensity level. With the lighting load 116 at the desired intensity level, the user may then “quad tap” actuator 16, i.e., tap actuator 16 four times in rapid succession (e.g., less than ½ sec between taps). The LED corresponding to the level at which the lighting load 116 was initially set will then blink twice, and the microprocessor will cause the selected light intensity level to be stored in memory as the protected preset intensity level. Note that the quad tap is actually a “save” operation. That is, the dimmer enables the user to save in memory a value associated with a current light intensity level as a protected preset value. Thereafter, whenever the lights are turned on, the dimmer will cause the lighting load 116 to go to the stored preset intensity level. Protected preset maybe deactivated by another quad tap.
It has been found that, in such a dimmer, protected preset may be accidentally implemented. That is, a user may quad tap actuator 16 and activate or deactivate protected preset inadvertently. Also, the quad tap enables the user to set only one parameter associated with only one feature the dimmer provides. It would be desirable, therefore, if apparatus and methods were available that enabled a user of such a wallbox dimmer to program one or more features of the dimmer using only the limited user interface such a dimmer provides.